Pre-PAW
2026 WCPO Bigeye Assessment
Identify issues and priorities
Kyuhan Kim | SPC-OFP
13 November 2025
1. Review 2023 Issues
2. Identify Priorities for 2026
Spatial: 6R vs 9R?
Tag mixing: 1Q/2Q/3Q?
Some uncertainty around input data
Only 1,004 otoliths
Limited spatial and temporal coverage (mostly 2009-2018)
Continue age data collection
evaluate growth/mortality variability
explore regional traits
Add more otoliths collected by Japanese colleagues
Use tagging data to estimate growth?
Low tropical \(\leftrightarrow\) temperate movement
High mixing within tropical/temperate zones
Simulation study: 6-region vs 9-region performance
“areas-as-fleets” approach
Investigate model specifications causing this trend
“Model convergence is a significant issue for these complex models… jittering is an important process to refine and improve the best solution.”
“Jittered solutions achieved improved objective function values and notable changes to derived management quantities. This was cause for considerable concern.”
“Every grid model improved through jittering — none was at a global minimum, even those 46 with positive definite Hessians.”
Docker image for reproducibility:
GitHub Actions for quality control and continuous integration:
All materials publicly available
Analysis: github.com/PacificCommunity/ofp-sam-2026-BET
Report: github.com/PacificCommunity/ofp-sam-2026-BET-report
Pacific Community (SPC)
Oceanic Fisheries Programme
Contact: kyuhank@spc.int
WCPO BET Annual Catches (1952-2021)
By Gear Type:
Trend: Relatively stable since 2000
Tropical regions dominate:
Pre-PAW: 2026 BET Assessment | SPC-OFP